The goal of this project is to develop a commercially available vaginal suppository containing a H2O2-producing strain of Lactobacillus for use in colonization of the vagina. Vaginal lactobacilli are the primary microbial defense against infection. Lactobacillus predominant vaginal flora is associated with decreased frequencies of gonorrhea and chlamydial infections. Women with H2O2-producing lactobacilli have fewer vaginal infections including bacterial vaginosis and trichomoniasis. While only half of women of child-bearing age are colonized by H2O2-producing lactobacilli, there are no commercially available products in the U.S. suitable as vaginal suppositories. During Phase I studies, a strain of Lactobacillus was selected based on adherence to vaginal epithelial cells, H2O2-production, growth characteristics and viability stability during storage. Pilot production methols to preserve these characteristics in a suppository format were developed. In this study, commercial scale cGMP production and packaging methods for the suppository will be optimized. Animal toxicity studies and a dose-ranging efficacy and safety study in women will be performed. An efficacious and safe Lactobacillus suppository for colonization of the vagina could lead to maintenance of an intact vaginal ecosystem resulting in decreased prevalence of genital tract infections among women of childbearing age. PROPOSED COMMERCIAL APPLICATION: A commercial suppository capable of re- establishing the optimal vaginal ecosystem could decrease occurrence of genital tract infections. There are 57.4 million women of child-bearing age (15-44 years old) in the U.S. Only half of these women are colonized with H. producing lactobacilli, a primary defense mechanism against genital infections. The commercial need is evidenced by the estimated 10 million office visits for vaginal complaints each year.